Toothbrush stem attachment

ABSTRACT

A molded plastic toothbrush stem attachment for a power hand appliance comprises a stem having an integral coupling at one end and laterally-extending bristles forming a brush at the other end. The coupling includes a flared section, a driving socket section and a pair of detent fingers. The fingers are disposed at rotational angles 90* from that of the brush, and their free ends have internal arcuate grooves and external arcuate projections. A portion of the flared section overlaps the socket section in spaced relationship and the socket is deeper than the overlap region, to facilitate one-piece molding. Tip portions of the flared section adjacent one finger are flat and non-symmetrical to the tip portions adjacent the other finger to enable proper orientation for automatic bristle insertion.

[ Dec. 23, 1975 ABSTRACT 3 Claims, 4 Drawing Figures PrimaryExaminer-Harvey C. Hornsby Assistant Examiner-James A. NiegowskiAttorney, Agent, or Firm-Pennie & Edmonds A molded plastic toothbrushstem attachment for a power hand appliance comprises a stem having anintegral coupling at one end and laterally-extending bristles forming abrush at the other end. The coupling includes a flared section, adriving socket section and a pair of detent fingers. The fingers aredisposed at rotational angles 90 from that of the brush, and their freeends have internal arcuate grooves and external arcuate projections. Aportion of the flared section overlaps the socket section in spacedrelationship and the socket is deeper than the overlap region, tofacilitate one-piece molding. Tip portions of the flared sectionadjacent one finger are flat and non-symmetrical to O Umted StatesPatent [191 Moret et al.

Inventors: Michel A. Moret; Jean-Pierre Musy,

both of Geneva, Switzerland [73] Assignee: Les Produits Associes, SA,Geneva,

Switzerland Dec. 20, 1972 Appl. No.: 316,980

15/176; 15/22 R; 403/322 Int. A46B 13/02 [58] Field of Search..........15/176, 145, 22; 128/50, 128/66; 403/315, 321, 326, 330, 377, 322

References Cited UNITED STATES PATENTS TOOTHBRUSH STEM ATTACHMENT [22]Filed:

the tip portions adjacent the other finger to enable proper orientationfor automatic bristle insertion.

U.S. Patent Dec. 23, 1,975 3,927,435

FIG.1

TOOTHBRUSH STEM ATTACHMENT BACKGROUND OF THE INVENTION This inventionrelates to a toothbrush stem attachment for a hand appliance for oralhygiene. It provides an attachment which can be easily attached andremoved, is securely held in place during use, and can be economicallymolded in one piece of plastic to which the bristles are subsequentlyaffixed.

U.S. Pat. No. 3,536,065 describes a unitary hydraulically-operated handappliance capable of both toothbrush and water jet operation by simplyinterchanging the appliance attachments. The appliance includes anhydraulic motor driven by liquid pressure pulses from a pump unit fortoothbrush operation, and a separate conduit actuable by a manual valvefor supplying the pressure pulses to a water jet attachment. Simplemeans for coupling attachments to the hand appliance are described.

Application Ser. No. 244,879 filed Apr. 17, 1972 now US. Pat. No.3,771,186 as a continuing application of Ser. No. 1 17,466 filed Feb.22, 1971 now abandoned, also describes an hydraulically-driven handappliance for personal hygiene which is capable of alternativelyrotationally oscillating a toothbrush attachment or supplying liquidpressure pulses to an appliance head such as a water jet attachment.

To permit attachment and removal, and use of different toothbrushattachments by different members of the family, a coupling arrangementis necessary. The coupling should be as simple and foolproof inoperation as possible, so that it can easily be used by children andwill not result in damage to the hand appliance or attachment ifcarelessly used. Also, it should be capable of rotational oscillation ina positive manner without undue wear, and should resist forces tendingto detach the brush from the motor unit when the bristles are pressedagainst the teeth. Finally, inasmuch as worn bristles will requirereplacement attachments, the attachment should be economical tomanufacture.

In the foregoing application coupling means are described in which thedriving and detent functions are separated, driving being by means of asquare socket in the toothbnish attachment and detent by means of springarms having outwardly extending hooks which engage in an annular groovein the motor unit. To remove the attachment, the spring arms are pressedinward to uncouple the hooks from the groove. Although such removal is asimple operation, some users may simply pull on the attachment withoutdepressing the spring arms. In such case the hook detents may be brokenoff, or become sufficiently worn so that they no longer functionproperly.

In application Ser. No. 228,574 filed Feb. 23, 1972 now U.S. Pat. No.3,851,984 by Jean-Pierre Crippa, coupling means is described having acoupling section and a coupling retaining member slidable thereon. Theretaining member includes a spring arm having an inwardly-extending hookwhich engages an annular lip on the motor unit. Cam surfaces on thespring arm and coupling section cooperate to disengage the hook as theattachment is pulled ofi. Although successful in operation, the use ofseparate parts require separate molding operations and then assembly,with resultant somewhat high manufacturing cost.

The present invention is directed to a toothbrush attachment which issimple and satisfactory in operation, and can be molded in one piece ofplastic material with subsequent attachment of bristles.

SUMMARY OF THE INVENTION In accordance with the invention, thetoothbrush stern attachment comprises a molded plastic stem having anintegral coupling at one end and laterallyextending bristles forming abrush at the other end. The coupling includes a flared section, adriving socket section extending beyond the flared section, and a pairof narrow longitudinally-extending resilient cantilever detent fingersradially spaced from the socket section and terminating between the endsof the flared and socket sections.

The socket section has a rotationally symmetrical exterior surface andan interior surface which is cylindrical at the open end thereof and isof non-circular cross-section deeper in the socket. The cylindricalportion aids in quiding the attachment onto the output member of a powerhand appliance, and provides a pivot for rotating the attachment to matewith the output member.

The fixed ends of the detent fingers are integral with the flaredsection and spaced back from the end thereof, and the sides of thefingers are spaced from the adjacent portions of the flared section. Thefree ends of the fingers have respective detent grooves on the insidethereof which are curved in arcs which are rotationally symmetricalabout the axis of the socket section.

' Advantageously the free ends of the detent fingers have outwardprojections opposite the detent grooves which strengthen the ends andprevent distortion of the grooves. The outer faces of the projectionsare curved in arcs which are rotationally symmetrical about the axis ofthe socket section. Preferably the fingers are disposed on oppositesides of the socket section at respective rotational anglesapproximately from the rotational angle of the brush. In case of playbetween the socket section and the appliance output member, thisdisposition guards against uncoupling when the brush is pressed againstthe teeth and possible jamming against an encircling member of the handappliance if such is present.

Also, advantageously, a portion of the flared section overlaps a portionof the socket section in spaced relationship therewith, and the insideof the socket section extends into the stem beyond the portionoverlapped by the flared section. This facilitates one-piece molding bypromoting rapid and reasonably uniform cooling of all portions of theflared section, thereby avoiding distortion and reducing overall moldingtime. Preferably the tip portions of the flared section adjacent one ofthe detent fingers are flat and non-symmetrical with respect to the tipportions adjacent the other finger, to facilitate properly orienting themolded stem in automatic apparatus for inserting the bristles.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall view of anhydraulic hand appliance with toothbrush attachment in place;

FIG. 2 shows the front end of the hand appliance of FIG. 1 and thecoupling portion of the toothbrush attachment in longitudinalcross-section;

FIG. 3 shows the toothbrush attachment rotated 90 from its position inFIG. 2; and

FIG. 4 is an end view and partial cross-section taken along the line 4-4of FIG. 3.

DESCRIPTION OF THE SPECIFIC EMBODIMENT Referring to FIG. 1, an hydraulichand appliance of the type described in the aforesaid application Ser.No. 244,879 is shown. Liquid pulses are supplied through flexibleconduit 11 and the appliance is controlled by a slidable sleeve 12. Inthe position shown, sleeve 12 controls valves in the appliance 10 whichcause the toothbrush attachment 13 to be rotationally oscillated. In itsrearward position, sleeve 12 shuts off the appliance.

Referring to FIG. 2, the front end of the hand appliance is shown and issimilar to that shown in FIGS. 14-16 of the aforesaid application Ser.No. 244,879 except for the coupling arrangement. Briefly, the casing hasa cylindrical member 14 and a bearing 15 fixedly mounted therein. Sleeve16 is rotationally oscillated by an hydraulic piston motor in the rearof the appliance and a motion converter including a helical cam screw 17and cooperating nut section. Attached to the sleeve 16 is an outputmember having a cylindrical rear section 18 and a front section 19 whichis square in cross-section so as to drive a toothbrush attachment inrotational oscillation. Member 21 is fixedly attached to 14 and 15 andhas an annular projection 22 serving as a detent. An O-ring 24 providesa seal for a liquid jet attachment when used, but is out of contact withthe toothbrush attachment here shown.

Referring to FIGS. 2-4, the toothbrush attachment comprises a stemhaving an integral coupling at one end and laterally-extending bristles31 forming a brush at the other end. These ends may conveniently betermed rear and front ends, respectively. Several rows of tufts areused, as shown in FIG. 4, but only the center row is shown in FIG. 3 toavoid undue complexity of illustration. The coupling includes a flaredsection 32, a driving socket section 33 extending beyond the flaredsection, and a pair of narrow longitudinallyextending resilientcantilever detent fingers 34 extending beyond the flared section andterminating between the ends of the flared and socket sections.

The socket section 33 has arotationally symmetrical exterior surface,with the end 33' reduced in diameter to clear O-ring 24 and eliminatefriction therewith. The interior surface is cylindrical at the open end33 thereof, as shown at 35 in FIG. 4. Deeper in the socket, at 36, theinterior surface is square in cross-section to mate with section 19 ofthe appliance output member and, with the greater thickness of thesocket wall at 33", provides a strong driving connection. Althoughsquare cross-sections are preferred, other non-circular cross-sectionscould be used. The initial cylindrical inner wall 35 aids in guiding thecoupling onto output member 19 and provides a pivot for rotating theattachment to mate the square sections. Chamfers may be employed at thebeginning of square section 36, and on the end of member 19, tofacilitate attachment.

The fixed ends 34 of the detent fingers are integral with the flaredsection 32 and spaced back from the end thereof to provide sufficientresiliency for outward movement of the finger ends during attachment toand removal from the appliance 10. Slots 37 provide spacing between thesides of the fingers and the adjacent portions of the flared section.The free ends of the fingers have respective detent grooves 38 on theinside thereof which are curved in arcs (FIG. 4) which are rotationallysymmetrical about the axis of the socket section. This, together withthe narrowness of the fingets, allows the attachment to rotationallyoscillate without undue friction with detent ring 22.

The free ends of the detent fingers have outward projections 39 oppositethe detent grooves 38 which strenghten the ends and prevent distortionof the grooves. The outer faces of the projections are curved in arcswhich are rotationally symmetrical about the axis of the socket section,as best seen in FIG. 4. This permits maintaining adequate thickness overthe width of the finger, without contacting the control sleeve 12 inoperation.

In FIG. 2 it will be noted that control sleeve 12 overlaps projections39 in operation, and prevents sufficient outward movement of the fingersto disengage the detent surfaces. In a new attachment with well-fittingdetent grooves and close mating of the socket on the output member 19 ofthe appliance, the strength of the fingers may be made sufficient tohold the attachment in place despite the forces exerted on the couplingas the bristles are pressed against the teeth. However, as wear occurs,or if manufacturing tolerances are not sufficiently close, the holdingaction may be weakened. In such case it is desirable to avoid anyspreading of the fingers which will bring the projections'39 intocontact with sleeve 12, since this would not only wear the attachmentbut would add to the load on the motor and, if jarnmin g occurs, mightseriously impair the rotational oscillation of the brush. If theattachment is used with an appliance in which a control sleeve does notencircle the finger ends, it is desirable to avoid sufficient spreadingto uncouple the detents.

To guard against such adverse effects in case of play in the socketsection, the resilient fingers 34 are advantageously disposed onopposite sides of the socket section 33 at respective rotational anglesapproximately from the rotational angle of the brush formed by bristles31. Thus, in FIG. 4 the rotational angles of the fingers, indicated bydot-dash lines 41, 41', are at 90 from the rotational angle of thebrush, indicated by dot-dash line 42. From FIGS. 2 and 3, it will beappreciated that, as the brush is pressed against the teeth, the turningforces on the fingers are in the direction of the width thereof and areresisted by the side walls of the grooves. That is, the turning forcesattempt to turn the attachment about an axis which passes diametricallythrough the grooves of the two fingers, and the clamping of the groovesagainst the annular detent 22 in the appliance resists these turningforces and maintains the coupling despite some play in the socketsection.

On the other hand, if the brush were rotated 90 from that shown, theturning forces on the fingers would be parallel to the stem axis and thegroove in each finger would serve as a fulcrum for the groove in theother. Also, for a given amount of rocking allowed by play in the socketsection, there will be greater outward movement of the finger ends.

Thus, with the fingers and brush oriented as shown, if there is play inthe socket section there is less danger of the ends of the fingers beingforced outward to release the attachment, and less danger of the endsjamming against the control sleeve 12 when such a sleeve is employed inthe hand appliance.

As seen in FIG. 3, the ends 32' of the flared section overlap a portionof the socket section 33 in spaced relationship, as indicated by dashlines 43. Also, as seen in FIG. 2, the inside of the socket sectionextends into the stem beyond the portion thereof overlapped by theflared section. This facilitates molding in one piece, as

by injection molding, by reducing the thickness of the plastic materialin adjacent portions of the flared section so that rapid and reasonablyuniform cooling can be obtained in all portions of the flared section.Thus distortions due to markedly different rates of cooling are avoided,and the overall molding time reduced. This is of considerable importancein promoting economical manufacture.

As best seen in FIG. 4, the tip portions of the flared section adjacentone of the fingers, indicated at 44, are flat and non-symmetrical withrespect to the tip portions adjacent the other finger. This permitsproperly orienting the molded stem in automatic apparatus for insertingthe bristles, without requiring the attention of the operator.

As will be recognized by those skilled in the art, the entire stemincluding the coupling may readily be molded in one piece of plasticmaterial without complicated fixtures, thereby enabling economicalmanufacture. For example, a mold having a single inner member and a pairof mating outer members suffices. When the plastic has been injected andcooled, the outer members may be separated and the stem with theintegral coupling pulled ofi the inner member, the resiliency of thefingers allowing the pulling off. Holes 45 may be formed by the moldingoperation so that the entire attachment can be made in one operation,ready for insertion of the bristles. Suitable plastics are known in theart, such as nylon or an acetal resin sold under the trademark DELRIN byduPont.

We claim:

1. A toothbrush stem attachment adapted to be attached to and driven bya hand appliance having an opening for receiving said toothbrush sternand an annular projection for retaining the toothbrush stem to saidappliance, which attachment comprises a. a molded stern having anintegral coupling at the rear end thereof and laterally-extendingbristles forming a brush at the front end thereof,

b. said coupling including a flared section flaring three-dimensionallyoutwardly and rearwardly, a

driving socket section extending rearwardly beyond said flared section,and a pair of narrow longitudinally-extending resilient cantileverdetent fingers radially spaced from the socket section and terminatingbetween the rearward ends of the flared and socket sections,

0. said socket section having a rotationally symmetrical exteriorsurface and an interior surface which is cylindrical at the open endthereof and is of noncircular cross-section deeper in the socket,

d. a portion of said flared section overlapping a portion of said socketsection in spaced relationship therewith and the inside of the socketsection extending into the stern beyond the region of said overlapping,

e. said resilient fingers being on opposite sides of the stem with thefixed ends of the fingers integral with said flared section and forwardof the rear end of the flared section,

f. the sides of said fingers being spaced from the adjacent portions ofthe flared section,

g. the free ends of said fingers having respective detent grooves on theinside thereof which are curved in arcs which are rotationallysymmetrical about the axis of said socket section, said fingers beingadapted to extend over said annular projection, and

h. the free ends of said fingers having respective outward projectionsopposite said detent grooves with the outer faces curved in arcs whichare rotationally symmetrical about the axis of said socket section.

2. A toothbrush attachment according to claim 1 in which said resilientcantilever detent fingers are at respective rotational anglesapproximately from the rotational angle of said brush.

3. A toothbrush attachment according to claim 1 in which the tipportions of said flared section adjacent one of said fingers are flatand non-symmetrical with respect to the tip portions adjacent the otherfinger.

1. A toothbrush stem attachment adapted to be attached to and driven bya hand appliance having an opening for receiving said toothbrush stemand an annular projection for retaining the toothbrush stem to saidappliance, which attachment comprises a. a molded stem having anintegral coupling at the rear end thereof and laterally-extendingbristles forming a brush at the front end thereof, b. said couplingincluding a flared section flaring threedimensionally outwardly andrearwardly, a driving socket section extending rearwardly beyond saidflared section, and a pair of narrow longitudinally-extending resilientcantilever detent fingers radially spaced from the socket section andterminating between the rearward ends of the flared and socket sections,c. said socket section having a rotationally symmetrical exteriorsurface and an interior surface which is cylindrical at the open endthereof and is of non-circular cross-section deeper in the socket, d. aportion of said flared section overlapping a portion of said socketsection in spaced relationship therewith and the inside of the socketsection extending into the stem beyond the region of said overlapping,e. said resilient fingers being on opposite sides of the stem with thefixed ends of the fingers integral with said flared section and forwardof the rear end of the flared section, f. the sides of said fingersbeing spaced from the adjacent portions of the flared section, g. thefree ends of said fingers having respective detent grooves on the insidethereof which are curved in arcs which are rotationally symmetricalabout the axis of said socket section, said fingers being adapted toextend over said annular projection, and h. the free ends of saidfingers having respective outward projections opposite said detentgrooves with the outer faces curved in arcs which are rotationallysymmetrical about the axis of said socket section.
 2. A toothbrushattachment according to claim 1 in which said resilient cantileverdetent fingers are at respective rotational angles approximately 90*from the rotational angle of said brush.
 3. A toothbrush attachmentaccording to claim 1 in which the tip portions of said flared sectionadjacent one of said fingers are flat and non-symmetrical with respectto the tip portions adjacent the other finger.